Asked by: Ben Winsley, London
Space launches can have a hefty carbon footprint due to the burning of solid rocket fuels. Many rockets are, however, propelled by liquid hydrogen fuel, which produces ‘clean’ water vapour exhaust, although the production of hydrogen itself can cause significant carbon emissions. Rocket engines release trace gases into the upper atmosphere that contribute to ozone depletion, as well as particles of soot. Rocket launches are nonetheless relatively infrequent, meaning that their overall impact on our climate remains much smaller than aviation’s. But it’s not just our immediate environment: ‘space junk’ is a growing concern as disused satellites and other objects accumulate in our planet’s orbit.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.